Struct PartialKeyPath 

pub struct PartialKeyPath<Root> { /* private fields */ }

PartialKeyPath - Hides the Value type but keeps Root visible Useful for storing keypaths in collections without knowing the exact Value type

Why PhantomData?

PhantomData<Root> is needed because:

1. The Root type parameter is not actually stored in the struct (only used in the closure)
2. Rust needs to know the generic type parameter for:
   • Type checking at compile time
   • Ensuring correct usage (e.g., PartialKeyPath<User> can only be used with &User)
   • Preventing mixing different Root types
3. Without PhantomData, Rust would complain that Root is unused
4. PhantomData is zero-sized - it adds no runtime overhead

Implementations

impl<Root> PartialKeyPath<Root>

pub fn new<Value>( keypath: KeyPath<Root, Value, impl for<'r> Fn(&'r Root) -> &'r Value + 'static>, ) -> Self

where Value: Any + 'static, Root: 'static,

pub fn from<Value>( keypath: KeyPath<Root, Value, impl for<'r> Fn(&'r Root) -> &'r Value + 'static>, ) -> Self

where Value: Any + 'static, Root: 'static,

Create a PartialKeyPath from a concrete KeyPath Alias for new() for consistency with from() pattern

pub fn get<'r>(&self, root: &'r Root) -> &'r dyn Any

pub fn value_type_id(&self) -> TypeId

Get the TypeId of the Value type

pub fn get_as<'a, Value: Any>(&self, root: &'a Root) -> Option<&'a Value>

Try to downcast the result to a specific type

pub fn kind_name(&self) -> String

Get a human-readable name for the value type Returns a string representation of the TypeId

Trait Implementations

impl<Root: Clone> Clone for PartialKeyPath<Root>

fn clone(&self) -> PartialKeyPath<Root>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.